Dendritic Cells Flashcards
What are the three subsets of DCs?
Convention, plasmacytoid and innflamatory
What are properties of Convention DCs?
Located at body surfaces and secondary Lymphoid tissues
Bring pathogenic material to draining LNs
Activate Naive T-cell responce
What are properties of palsmacytoid DCs?
Circulate in blood periphery
Recruited to inflammation sites
Have immunomodulatory role
Produce Type 1 Interferon
What are properties of Inflammatory DCs
Not found in steady state, only during Inflammation
Monocyte Derived
Increase antigen presentation during inflammation
Re-activate Memory T-cells in non-lymphoid tissues
Markers for cDC1s human and mouse
Role of cDC1
Human: CD141, XCR1, CLEC9A, CADM1.
Mouse: CD103/CD8, XCR1, CLEC9A, CADM1
Role: Cross presentation, production of IL-12 + INF gamma, TLR3 expression, Th1/Th2 generation
Markers for cDC2s in humans and mouse
Role of cDC2
Human: CD1c, CD11b, SIRP alpha
Mouse: CD24, CD11B, SIRP alpha
Role: DC4 T- Cell responce, IL-1B, IL-6, IL-23 production,
Expression of all TLR except TLR3 in mice and TLR9 in humans, Th2 and Th17 generation
Where are Conventional and Plasmatoid DCs derived from?
Common Dendritic Progenitors
Where are Inflammatory DCs derived from?
Monocytes
What is the Process of a DC immune responce?
DCs in pheripheral tissues pick up antigens and express them on MHCs
DCs then become mature and migrate to Draining lymph nodes via the lymphatic vessels
Present antigens to T-cells in lymph nodes
Whats the differences between mature and immature DCs?
Immature - high phagocytosis, Low MHC expression and low co-stimulatory molecules, Low CCR7
Mature: Low phagocytosis, high MHC expression and co-stimulatory molecules and high CCR7
What causes DC maturation?
PAMPS: Bacterial LPS (detected by TLR4) viral dsRNA (TLR3), Cytokines (TNF alpha and IL-1) and CD40 ligands
How can you generate DCs from peripheral blood?
Isolate CD14 monocytes,
Subject them to IL-4 and GM-CSF (6days) to get an immature DC
Subject them to PAMPs, TNFalpha, IL-1beta 24 hours to get mature DC
What is the fate of naive Th Cells based on the three signals 1,2 and 3?
Signal 1: MHC II expression of antigen to T-cell receptor leads to T-cell activation
Signal 2: CD80/CD26 on APC interact with T-cell CD28, this promotes T-Cell survival, IL-2 production and clonal expansion
Signal 3: APC secrete cytokines, this polarieses T-Cells
What cytokine signals produce which Th Cell responce?
What Do these Th cell responses target?
IFNgamma - Th1 - Intracellular pathogens, virusus, mycobacterium, activation of macrophages
IL-4- Th2- Extracellular pathogens, helminths,Aid B-cells
1l-17-Th17-Bacteria/fungi (surface tissues recruit neutrophils).
What type of T-Cell responce can DCs trigger in cancer and autoimmune immunotherapy?
Effector T-cells - cancer
Tregs - Autoimmuntiy
How can DCs be isolated?
cd14+ monocytesm, DC generation, DC antigen loading,
Antigen presentation to T-cells
Maturation state of DCs determines T-Cell response
Differecne between immature, semi mature and mature DCs in terms of MHC II, CD80/86, IL-12/IL-6 and TGF beta
Immature: MHC II + , CD80/86 - , IL-12/IL-6 - , TGFbeta -
Semi- Mature: MCH II + + , CD80/86 + , IL-12/IL-6 - , TGFbeta ++
Mature : MHC II ++, CD80/86 ++, IL12-IL-6 ++ , TGFbeta +
Why use DCs for cancer therapy?
DC have ability to remove rare events
Other surgeries/ radio and chemotherapy dont always remove residual cancer cells which can re-occur. DC can clean up these residual cancer cells.
DCs non-toxic and target heterogenous tumors
can have multiple antigen targets and epitope spreading
Negative of DCs for cancer therpay
Not good at removing bulky tumors
Goals of DC based cancer therapy
1) Cancer specifc T-cell expansion
2) T-cells with appropriate Effector function
3) T-cells migrate to relevent tumor tissues
Problems of DC cancer therapy?
No pro-innflamtory signals in cancers (eg no TLR ligands)
Tumors produce suppressive factors ie IL-10 TGFbeta which can lead to DC dyfunction
Cancer patients - expansion and hyperactivation of Tregs
Desired DC features for cancer therapy
High MHC II/Co-stimulatory factors
High IL-12 to induce CTL and Th1
High CCR7 so DC migrate to lymph nodes
Attraction of desired immune cells - NK cells, CTL and CTH but avoid Tregs by appropriate chemokine profile eg high CCL5,CXCL10,CCL22
Resistant to supression - Final maturation
3rd Generation DC cancer therapy
1st decribed by Radomski et al.,
CD14 monocyte isoloation, treat with IL-4 and GM-CSF, Which produces immature DCs. Treat with TNF alpha IL-1 INFgamma/alpha and Poly I:C to stimulate TLR3
Called it alphaDC1
What was AlphaDC1s profile?
What are proplems with 3rd Gen DC cancer therpay?
MHC II +++, CD80/86+++ , CCR7+++, IL-12+++, CCL5/CXXL10 +++
Problems: Monocyte derived, so dont migrate well to lymph nodes (aprox 4%)
4th Gen DC cancer therapy
Problems with it
Same as 3rd gen but used blood plasmacytoid or conventional DCs. This means no culture period needed and better migratory power to LN1
(1st clinical trail improved progression free survival in melanoma patients)
Problems: Semi maturen DCs unstable and can make CD4 T-cells tolerogenic and inducy CD8 T-cell immunity.
What are the properties of tolerogenic DCs?
MHC II ++ , CD80/86 + , TNFalpha / IL-12 - , TGFbeta/IL-10 ++
How can you stabilise tolDCs
CD14 monocytes + IL-4/GM-CSF
You then get immature DCs
Culture with IL-10 and TGF beta
Then can use Drugs such as Dex, Vit3D AND BAY11-7082
What has TolDC induction shown in animal models?
Delay of Transplantation rejection and or prevntion of autoimmue diseases (autoimmune diseases can be cured)
Work At Newcastle with tolDCs to treat RA purpose
re-establish tolerogenic responce against self antigen without affecting protective immunity
Pros and conc of TolDCs for RA treatment
Pros: Low toxcicity, Targeted immunosuppression, Potential to restore underlying defect.
Cons: Custimised and therefor high COST, Autoantigens still not known, Risk of enhancing autoimmune responce
What they wanted to achive with tolDC treatment forn RA
Presentation of self autoantigen (high signal 1)
Low co-stimulation, but this maybe needs to be changed to high (as co stimulation signal 2 needed for Treg induction)
Anti-innflammatory cytokine profile (signal 3)
How they achived tolDCs
Day 0 - CD14 monocyte isolation and culture with IL-4 and GM-CSF
Day 3 - Culture of DCs with Dex, IL-4 and GM-CSF to generate immature DCs
Day 6 - Immature DC cultured with Dex, Vit3D and TLR-4 ligand
Day 7 - Mature TolDC
What was the phenotype and cytokine profile of the TolDCs used for the RA treatment at newcastle?
Phenotype : MHC II +++, CD80/86 ++, CD83+/-
Cytokine Profile: IL-10+++, TGFbeta +++ , IL-12 - , IL-23/IL-6/TNF +
These DCs very good at polarising T-cells to inflammatory responce phenotype in mice.
Mice showed reduced IL-17 and Very high IL-10
AuTo DECRA
Phase 1 clinical trial. Unblinded, placebo controlled dose escalation trail to assess safety, tolerability, feasibility and efficacy of biomarkers.
Conclusion - Safe (no knee flares) TolDCs local not systemic.
